To confirm the stars' dizzying tango, Roelofs and colleagues turned to the world's second largest optical telescope, at the W. M. Keck Observatory in Hawaii, where they measured "wobbles" in the system's brightness.

"The amplitude of the wobble gives you an idea of the orbit period and the masses" of the stars, co-author Steeghs said.

What's more, light emissions from the stars were found to be moving in opposite directions, as such emissions would for two orbiting bodies, cinching the case for a binary system.

HM Cancri's record-breaking orbit couldn't get much quicker, Steeghs added, since the stars would merge if they got any closer, triggering a massive explosion known as a type Ia supernova. (Related: "New Type of Supernova Discovered.")

Overall, he said, three minutes would be the fastest a binary white dwarf system could get.